Antiwear agent and lubricating composition thereof

Abstract

The present invention relates to a lubricating composition containing a dicarboxylic acid ester or a dicarboxylic acid amide as an antiwear agent. The invention further provides a lubricating composition suitable for the mechanical device such as an internal combustion engine.

1. A method for lubricating an internal combustion engine comprising supplying to the engine a lubricating composition comprising:
 (a) an oil of lubricating viscosity; 
 (b) 0.1 wt % to 5 wt % of malonic acid di-hydrocarbon ester, wherein each hydrocarbon group independently is a C 6  to C 20  linear or branched alkyl group, and 
 (c) a phosphorus-containing antiwear agent, wherein the internal combustion engine is a 2-stroke or 4-stroke engine. 
 
     
     
       2. The method of  claim 1 , wherein the oil of lubricating viscosity is an API Group I, Group II, or Group III oil, or mixtures thereof. 
     
     
       3. The method of  claim 1 , wherein the oil of lubricating viscosity is an API Group I, Group II, Group III, or Group IV oil, or mixtures thereof. 
     
     
       4. The method of  claim 1 , wherein the lubricating composition is further characterised as having at least one of (i) a sulphur content of 0.8 wt % or less, (ii) a phosphorus content of 0.2 wt % or less, or (iii) a sulphated ash content of 2 wt % or less. 
     
     
       5. The method of  claim 1 , wherein the lubricating composition is characterised as having (i) a sulphur content of 0.5 wt % or less, (ii) a phosphorus content of 0.1 wt % or less, and (iii) a sulphated ash content of 1.5 wt % or less. 
     
     
       6. The method of  claim 1 , wherein the lubricating composition further comprises at least one of a friction modifier, a viscosity modifier, an antioxidant, an overbased detergent, a succinimide dispersant, or mixtures thereof. 
     
     
       7. The method of  claim 6 , wherein the friction modifier is selected from the group consisting of long chain fatty acid derivatives of amines, fatty esters, fatty epoxides; fatty imidazolines; amine salts of alkylphosphoric acids; fatty alkyl tartrates; fatty alkyl tartrimides; and fatty alkyl tartramides. 
     
     
       8. The method of  claim 1 , wherein the lubricating composition further comprises a molybdenum compound. 
     
     
       9. The method of  claim 8 , wherein the molybdenum compound is selected from the group consisting of molybdenum dialkyldithiophosphates, molybdenum dithiocarbamates, amine salts of molybdenum compounds, and mixtures thereof. 
     
     
       10. The method of  claim 8 , wherein the molybdenum compound provides 5 ppm to 300 ppm of molybdenum. 
     
     
       11. The method of  claim 1 , wherein the lubricating composition further comprises an overbased detergent. 
     
     
       12. The method of  claim 11 , wherein the overbased detergent is selected from the group consisting of phenates, sulphur containing phenates, sulphonates, salixarates, salicylates, and mixtures thereof.